An individual often desires to change the ordinary straightness of the hair into a curl or wave pattern. This change in the configuration of the hair can be relatively permanent or can be temporary depending upon the process used to treat the hair. To permanently alter the configuration of the hair, the hair is subjected to a process that realigns the configuration of the hair through chemical bond breaking and reformation. Although this process provides a relatively permanent change in hair configuration, the process also tends to damage the hair. To temporarily alter the configuration of the hair, the hair is subjected to a predominantly mechanical realignment of the hair to a new configuration. The new hair configuration is held in place by a non-reacting chemical treatment. This mechanical process is non-damaging to the hair, however, the new configuration of the hair usually is lost as soon as the hair is wetted, such as during shampooing. As a consequence, the hair must be reset almost daily. Therefore, it would be advantageous to provide a hair treating composition for use in a process to alter the configuration of hair that does not damage the hair and yet provides a semi-permanent hair configuration, thereby precluding daily hair setting and hair treating.
In general, the permanent waving of human hair is achieved by chemically breaking the sulfur-to-sulfur, or disulfide, bonds that occur naturally in the cystine component of human hair, and then reforming the disulfide bonds while the hair is wrapped or curled on rods. The sulfur-to-sulfur bonds present in the cystine component of human hair serve to maintain the hair in a naturally straight or naturally curly configuration. Therefore, in order to permanently reshape the hair into a lasting, different configuration, a significant percentage of the sulfur-to-sulfur bonds must be broken and then reformed after the hair is reconfigured into a desired configuration, such as wrapped around a suitable mandrel or roller. In general, the sulfur-to-sulfur bonds of cystine are broken with a composition containing a reducing agent. Then, after the hair is wound into a curl formation around a rod or roller, the disulfide bonds are relinked or reformed while the hair is in the curl configuration by contacting the newly configured hair with an oxidizing agent, such as hydrogen peroxide or a water-soluble bromate.
Different reducing agents, dependent upon the pH of the permanent wave process, are used effectively to break the cystine disulfide bonds that cross-link human hair protein. Generally speaking, the so-called acid permanent wave compositions, having a pH of from 6.5 to 8.5, include reducing agents such as the bisulfites, like ammonium bisulfite, or glycerol monothioglycolate that are capable of breaking the cystine sulfur-to-sulfur bonds at lower pH ranges. The so-called alkaline permanent wave compositions, having a pH in the range of about 7.5 to 9.5, require an alkaline salt of thioglycolic acid, such as ammonium thioglycolate. In the alkaline process, the free alkali of the permanent wave composition penetrates and swells the hair shaft for easier penetration by the reducing agent in order to break the cystine sulfur-to-sulfur bonds. Overall, the alkaline permanent wave compositions produce a stronger, longer lasting curl, whereas the acid permanent wave compositions provide a softer feel but a shorter curl duration.
Human error is one of the primary problems associated with the permanent waving process. In applying the permanent waving lotion, if the beauty operator allows the reducing agent to contact the hair shaft for the incorrect period of time, too many or too few of the disulfide bonds in the hair shaft are broken. The net effect is therefore either seriously damaged hair or hair that has not been treated sufficiently to achieve a permanent wave with long lasting potential. Often the beauty operator has difficulty in determining the correct amount of time that the permanent wave composition should contact the hair because the reducing agent reaction, on the breaking of the disulfide bonds, is dependent upon the amount of heat applied to the hair, the concentration of reducing agent, the pH of the lotion applied, and the condition of hair.
Perhaps the most difficult factor for the beauty operator to assess in determining how long to allow the reducing agent to contact the hair is the condition of the hair at the time of the permanent wave. It is well documented in the literature and the prior art that the hair can be damaged by abuse of hair treating chemicals, such as shampoos, permanent waves, tints, frosts, bleaches, and particularly any hair treatment involving the use of hydrogen peroxide; mechanical hair treatments, such as with thermal appliances; and environmental conditions, like climate and pollution. It is also well known that damaged hair, depending upon the stage and degree of damage to the hair, has significantly different chemical activity to reducing agents than normal or undamaged hair. Therefore, the time of contact between the reducing agent and the hair is important because if too many of the sulfur-to-sulfur bonds in the hair are broken by the reducing agent, the hair will be seriously weakened and may disintegrate.
Ideally, a sufficient number of the sulfur-to-sulfur bonds in the cystine in the hair shafts should be broken in order to give the hair the capability of being reshaped to any desired configuration such as curled around a rod or roller, and the capability of retaining this shape. If too few of the disulfide bonds are broken, the natural configuration of the hair will predominate, causing the hair to retain its previous normal shape because the predominant prior, or natural, bonds in the hair will dictate that the hair remains in its old configuration or shape.
Hydrogen bonds, or the type formed in a hair setting process as opposed to a permanent waving process, are physically broken when wet hair is stretched and wrapped around a roller. When the hair is dried, the hydrogen bonds are reformed in a curled position or shape to set the hair. While the hydrogen bonds act to hold the hair in the new configuration, the covalent disulfide bonds present in cystine are much stronger than the hydrogen bonds and, to a much greater extent than hydrogen bonds, control the ultimate configuration of the hair.
In order to successfully provide a satisfactory permanent wave in the hair, the cystine disulfide bonds, reformed in the hair in the new or curled configuration when the hair is oxidized with the neutralizing agent, should outnumber the cystine disulfide bonds of the old hair configuration. Therefore, when permanent waving, it is desired that a sufficient number of new disulfide bonds, in a new hair configuration, are formed during permanent waving to outweigh the number of old, remaining disulfide bonds that tend to form the hair into its prior or natural configuration, either straight or naturally curled.
Therefore, generally, when permanent waving the hair, the reducing agent lotion is applied to the hair after shampooing the hair, and either before or after the hair is wrapped around suitable rollers. After taking a "test curl" to determine whether the reducing agent has been in contact with the hair for a sufficient time period, the hair is rinsed thoroughly with water while the hair is still on the rollers or rods. Thus, while the hair remains on the rollers or rods in the new, rolled configuration, a neutralizing agent is applied to oxidize and reform the disulfide bonds. The neutralizing agent contains an oxidizing agent, such as hydrogen peroxide or a bromate salt, in order to reform the sulfur-to-sulfur, or disulfide, bonds to leave the hair in a new, relatively permanent configuration that lasts for from about 2 months to about 4 months. The neutralizing agent remains on the hair for approximately 5 to 10 minutes and then is rinsed from the hair. The rods can be removed either before or after rinsing out the neutralizing agent.
However, an individual often does not desire to produce a hair configuration that is relatively permanent, but would prefer to have a more transitory configuration that can be changed readily without having to undergo a second potentially hair-damaging permanent wave process in order to change the relatively permanent hair configuration imparted by the first permanent wave process. In this case, the individual prefers only to set the hair in a particular style for a relatively short time. However, normal hair can be so fine and limp, and so lacking in body, that the hair does not hold a hair set well. Furthermore, the hair can become even less bodied and can be weakened further as a result of being subjected to chemically active hair treatments, such as the permanent waves and tints described above. Additionally, hair can be weakened even further by other contributing factors, such as bleaching by sun exposure and/or chlorinated swimming pool water.
Normal hair is usually hydrophobic. However, many of the chemically active hair treatments remove the natural hydrophobic components from the hair. As a result, as the hydrophobicity of the hair decreases, the relative porosity of the hair increases and the hair tends to absorb water and swell more readily. In such a weakened and porous state, the water-swollen hair is more vulnerable to stretching and breaking.
Since hair setting is basically the process of shaping wet hair by the steps of stretching the hair by curling the hair, fixing the hair in place by drying, then combing to give the finishing touches to provide the desired hairstyle, the overall condition of the hair is an important factor in achieving an acceptable hair set. In particular, the setting of wet hair can be accomplished by making flat curls from strands of hair and fixing the curls with hairpins to produce "pin curls". Similarly, the wet hair can be set by using any of a variety of rollers or curlers to mechanically fix the hair. In either case, the winding of the wet hair is followed by drying, either by ambient air drying, electric drying or hot air drying.
The inherent problem encountered in hair setting is the natural tendency of the hair to return to its natural shape. For example, the set hair returns to its natural shape almost immediately if moistened. Likewise, high humidity conditions accelerate the tendency of the hair to return to its natural shape. Therefore, intensive efforts have been directed to providing a hair set with sufficient holding power to maintain the designed hair style until at least the next shampoo, and therefore giving the hair set a degree of permanency.
As shown by the natural tendency of hair to return to its natural shape, hair is an elastic structure. As a result, the slight deformations in the hair structure resulting from setting the hair are completely reversible. However, the rate of return of the hair to its natural shape is dependent upon the method used to deform, or set, the hair. Hair sets performed with wet strands of hair being rolled tightly, either in curls around the finger or on curlers, followed by drying the hair and in unrolling the curlers after drying, corresponds to the release of the hair from a deformation-causing load. The deformation, or set, obtained can last for several days, but the set will not be retained if the hair is wetted.
The observations of hair deformation and relaxation are related to physical and chemical changes in the protein structure level of hair. Sufficient stretching of the hair causes partial transformation of the .alpha.-keratin protein structure of the hair into the .beta.-keratin protein structure of the hair. This structural transformation is accompanied by a shift in relative position of the polypeptide chains that is facilitated by water moistening the hair. The shift in position of the polypeptide chains therefore disrupts the ionic and hydrogen bonds in the hair. During the drying procedure, new ionic and hydrogen bonds are formed that block the return to the .alpha.-keratin protein structure of hair. Gradually, the new protein linkages give way under natural forces, such that the hair returns to its original state and length. If the hair is moistened, the return to the .alpha.-keratin form is virtually immediate.
Therefore, investigators have sought to delay the combined action of natural forces and moisture that cause the hair to return to its original state by utilizing solutions containing naturally-occurring or synthetic polymers. When applied to the hair from aqueous or aqueous/alcoholic solutions, the polymers leave a film on the hair after drying. The polymeric film promotes cohesion and gives stability to the hair set, and therefore setting lotions containing polymers have been devised to maintain the hold of the hair set. The principal objective of the setting lotion is to cover the styled hair with an invisible polymeric film that will give the styled hair a degree of rigidity and protect the hair style against wind and humidity.
Hair spray products act in a similar manner. The hair spray products are applied to wet hair and generally are not rinsed out. Like hair setting lotions, the hair spray contains polymers, or mixtures of polymers, that remain fixed on the hair and affect the hair in various ways. For example, a "mechanical" effect is exerted on each individual hair. The film-forming polymers are used to provide a flexible sheath of polymeric film on the hair after drying, and therefore, for mechanical reasons, retard the return of each individual hair to its natural shape. In addition, the polymeric film provides an overall stiffening of the hair. The hair behaves as if the individual hair strands are welded together, and the final hairstyle has better cohesion, therefore resisting the natural forces that return the hair to its natural shape. Finally, the polymeric film protects the hair from humidity. The ability of the polymeric film to attract and absorb water is preferably minimal, such that the polymeric film retards moisture uptake by hair and retards the return of the hair to the .alpha.-keratin hair protein structure.
The general principles of hair setting are thoroughly discussed by C. Zviak, in The Science of Hair Care, Marcel Dekker, pp. 149-181 (1986). Zviak reviews both the polymers used in hair setting products and the formulation principles used to produce a hair set product that provides such beneficial hair set properties as improved hair style hold, easy application and combing, quick drying and non-stickiness, good hair body and bounce, increased hair volume and gloss, and hydrophobicity. It is evident that in the formulation of any end-use product, some of these benefits must be sacrificed to some degree to achieve a competing benefit. Therefore, the formulation of hair set products has proved difficult, and, as a result, hair set products have been developed in a variety of product forms.
The prior art reveals that nonionic, cationic and anionic polymers have been used in hair set products, with the anionic polymers providing the best hair set results. However, anionic polymers also have disadvantages, such as high water solubility, therefore low hydrophobicity, and low substantivity to hair fibers, therefore easy elimination from the hair by combing and brushing. As a result, investigators have continued to search for compounds and compositions that provide the benefits of an anionic surfactant-based hair set product plus an improved durability of the hair set. As previously mentioned, to overcome some of the inherent disadvantages of the polymers utilized to set the hair, hair set products are made available in diversified forms in an attempt to minimize the drawbacks of the particular polymer used in the formulation. For example, hair set products are available as plasticizing lotions, plasticizing gels, aerosol foams, all-purpose lotions, hair sprays, holding lotions, conditioners and shampoos.
Although commercially available products relying upon polymeric materials produce bodying effects on the hair, these products usually do not provide improvements in hair hydrophobicity against the known adverse effects of humidity in maintaining a hair style. In some cases, the hair treating products make the hair hard to comb or can absorb moisture themselves. One other effort to make hair hydrophobic is to apply oily hair dressings and creams to the hair, wherein the oily product is left on the hair to act as a physical barrier against moisture uptake. However, these oily products provide only a temporary barrier that is removed when the consumer washes her or his hair. In addition, these oily products frequently impart the hair with a dull coating, thereby sacrificing the bodying benefits desired by persons having fine, limp, porous hair. Consequently, in using presently available commercial products, consumers must sacrifice certain desirable physical characteristics of the hair in order to achieve or improve other desirable physical characteristics.
The present invention relates to a composition and method of treating the hair to condition the hair and to improve the physical properties of the treated hair. It has been found that by treating the hair with a composition comprising a protein having a sufficient amount of an amino acid having a disulfide linkage, such as a keratin-based protein that includes the amino acid cystine, the hair is conditioned and the physical properties of the hair are improved such that the hair will retain the shape of the hair set and will not revert to its natural shape upon contact with moisture. Furthermore, surprisingly and unexpectedly, hair treated with the composition of the present invention still will retain the shape of the hair set after several subsequent shampooings. Thus, the improved hair set retention properties imparted to the hair upon treatment with the composition of the present invention obviates the need to treat the hair each day or after each shampooing. In addition, the method and composition of the present invention provides a semi-permanent hair set that avoids the hair-damaging, reduction/oxidation permanent wave processes.
Proteins have been used in the hair care industry for a number of years. Presently, several commercial end-use hair-care products include proteins in order to provide some functional or esthetic benefit to the hair care product. The proteins used in hair care products differ in their physical properties, appearance and functional properties depending upon the source of the protein and the method used to hydrolyze the protein. For example, silk polypeptides, silk amino acids, hydrolyzed animal keratin, collagen and soya proteins each exhibit different physical and chemical properties and each has been used in hair care products to exploit the particular advantages of that protein. Furthermore, derivatized proteins, such as steardimonium hydrolyzed animal protein and triethanolamine lauroyl animal keratin amino acids are available specifically for use in cationic and anionic systems, respectively, because these derivatized proteins are considered to have a higher affinity for hair than the native underivatized protein. Generally, proteins and protein derivatives are used as conditioning agents to improve one or more of the following hair properties: combability, sheen, manageability, texture, body, and strength/elasticity.
Usually, the interaction between the hair and a protein is purely ionic in nature as a result of hydrogen bonding and some van der Waal interactions. Consequently, the bonds between the hair and the protein are easily broken by the moisture in air or water. Therefore, as in the usual synthetic polymer-based hair setting composition, the protein-based hair setting composition shows poor wash-fastness and is easily removed by wetting or shampooing the hair. As a result, the conditioning effects and hair set retention properties imparted to the hair by most protein-based hair setting compositions is only temporary.
However, a covalent bond between a protein and the hair can be formed if the protein includes an amino acid having a sulfur-to-sulfur, or disulfide, linkage, like the disulfide linkage present in the amino acid cystine. Normally, such proteins are applied to the hair in a redox system, like the redox systems used in a permanent wave process as described above, in order to provide a hair set and hair conditioning properties to the hair. An example of a protein applied to the hair in a permanent wave process is the protein sold under the brandname KERASOL, available from Croda Inc., N.Y., N.Y. KERASOL is a relatively high molecular weight keratin-based protein prepared by the cold hydrolysis of cattle hooves, and contains about 0.6% by weight of the amino acid cystine. Typically, KERASOL is applied to the hair as a post-reduction step in the permanent waving process. As will be described more fully hereinafter, a significant improvement in the condition of the hair is perceived if the KERASOL protein is applied to the hair either immediately after application of the reducing thioglycolate lotion or after subsequent rinsing of the reducing lotion from the hair. Furthermore, it has been disclosed that a cystine-containing protein can be added directly to the reducing thioglycolate solution to produce cystine residues in the thioglycolate solution that can be applied, thus subsequently covalently bonded, to the hair to impart superior conditioning properties.
A protein including a sufficient amount of an amino acid having a disulfide linkage is known to covalently bond to the hair when the protein is applied during a permanent wave process. The prior art teaches that proteins including an amino acid having a disulfide linkage are substantive to the hair, but that these proteins will not covalently bond to the hair when applied from non-reactive vehicles, such as shampoos and conditioners. To achieve covalent bonding between the cystine-containing protein and the hair, the prior art teaches that it is necessary to break the cystine disulfide bonds present in the hair keratin by a permanent wave process, to apply the cystine-containing protein at an appropriate step in the permanent wave process, and then to reform the cystine disulfide bonds, both within the hair and between the hair and the cystine-containing protein during the neutralization step of the permanent wave process. The prior art consistently emphasizes that if the cystine-containing protein is not applied at the appropriate stage of the permanent waving process, that the cystine-containing protein can not covalently bond to the hair through disulfide linkages.
For example, J. Chester and G. Mawby, in the publication "Permanent Hair Conditioning", Manufacturing Chemist, April 1987, pp. 53 and 55, teach that a permanent hair-conditioning effect can be achieved by covalently bonding a suitable conditioning agent to the hair keratin. The authors used a hydrolyzed keratin-based protein, containing both the amino acid cystine and cystine residues, as the conditioner, and covalently bonded the sulfur atoms present in the cystine residues of the keratin-based protein to the sulfur atoms present in the cystine residues of the hair by a reduction/oxidation treatment, such as a permanent waving process. As will be described more fully hereinafter, the authors found that a permanent conditioning effect is achieved when the cystine-containing protein was applied to the hair at any of the steps in a permanent waving process before the application of the oxidizing lotion. The authors likewise found that no permanent conditioning effect was achieved if the cystine-containing protein was applied after the application of the oxidizing lotion. Therefore, the cystine-containing protein had to be applied to the hair when the hair was in its reduced state, such that the sulfide moieties of the reduced hair could react with the disulfide bonds, or the reduced sulfide moieties, of the cystine-containing protein to form a covalent bond. The authors teach that the formation of a covalent bond between the hair and the cystine-containing protein is not possible after the oxidizing lotion is applied to the hair because the oxidizing lotion converts the reactive sulfide moieties of the reduced hair and of the keratin-based protein back to the relatively unreactive disulfide linkages of the natural hair and of the protein. The authors further found that maximum amount of covalent bonding of the hair to the cystine-containing protein occurred when the cystine-containing protein was applied to the hair just prior to application of the oxidizing lotion of the permanent waving process, and that no covalent bonding occurred when the cystine-containing protein was applied after the application of the oxidizing lotion of permanent waving process.
A. K. Puri and R. T. Jones, in "An Approach To Permanent Hair Conditioning", Preprints of the XIVth I.F.S.C.C. Congress, Barcelona, Vol. II, pp. 1153-1176 (1986), also showed the necessity of having first to reduce the hair, such as with a thioglycolate solution, before applying a protein that includes an amino acid having disulfide linkages to the hair, in order to form a covalent bond between the hair keratin and the protein. The authors similarly reported that covalent bonds between the hair and the protein did not form if the protein was applied to the hair after application of the oxidizing solution of the permanent waving process.
Karjala, in U.S. Pat. No. 3,842,848, teaches that improved conditioning properties are imparted to the hair by adding a cystine-containing protein directly to a thioglycolate solution in order to covalently bond the disulfide-containing protein to the hair. The method of Karjala, wherein the hair is treated with a reducing solution, that further includes a cystine-containing protein in order to break the disulfide bonds present in the hair keratin, is very similar to the normal permanent wave process. Then, a subsequent treatment with an oxidizing agent reforms the disulfide bonds that occur naturally in the hair, and further forms disulfide bonds between the hair and the cystine-containing protein that was added to the reducing solution in order to impart permanent conditioning properties to the hair.
A related method is disclosed in U.K. Patent Application GB 2,114,616, wherein a semi-permanent hair conditioning effect is achieved by precipitating a complex formed through the interaction between a cationic polymer that is present in the reducing solution and an anionic detergent that is present in the neutralizer solution onto the hair fibers. This method differs from the method of the present invention in that a covalent bond does not form between the protein-based conditioning agent and hair fibers to impart a more permanent hair conditioning effect. U.K. Patent Application GB 2,160,194 likewise teaches improving the condition of hair, skin or nails by a process of reducing the hair, rinsing the hair, applying an aqueous solution of a cystine-containing protein hydrolyzate to the hair, then applying a neutralizing solution to the hair. This process, however, damages the hair as a result of the reduction-oxidation steps required to covalently bond the cystine-containing protein to the hair. S. Naito, et al. in "Sorption Of Keratin Hydrolyzate To Hair And The Cosmetic Effect", Preprints of the XIVth I.F.S.C.C. Congress, Barcelona, Vol. II, pp. 1178-1193 (1986), demonstrates that the keratin-based hydrolyzates are in fact covalently bound to the hair if the hair first is reduced, then oxidized.
In contrast to the relatively permanent hair set retention properties afforded by permanent wave processes, to date, the compositions and methods used only to set hair have suffered from poor set retention times, from sacrificing one beneficial hair property in order to achieve another beneficial hair property, and/or from abnormally long times to treat the hair. Similarly, the compositions and methods used to permanently wave the hair have suffered from the disadvantages of serious hair damage due to the reduction-oxidation process coupled with operator error, such as too strong of reduction solution or too long of a contact time. Accordingly, prior to the present invention, no known method or composition has been employed to effectively condition hair within a few minutes and, simultaneously, to provide a semi-permanent hair set that is preserved through several shampooings subsequent to the hair conditioning and setting treatment.
Therefore, in accordance with the present invention, hair conditioning and hair set retention properties are surprisingly and unexpectedly improved by a method of contacting the hair with a composition comprising a protein having a sufficient amount of an amino acid having a disulfide linkage, such as a keratin-based protein that includes the amino acid cystine. The compositions of the present invention can be applied to the hair from an aqueous or a non-aqueous, such as alcoholic, vehicle at ambient temperature and are allowed to contact the hair for relatively short times to provide the benefits and advantages of a semi-permanent hair set without damaging the hair as a result of harsh reduction and oxidation reactions. Therefore, as will be demonstrated more fully hereinafter, the method and composition of the present invention both condition the hair and impart an esthetically-pleasing, semi-permanent hair set without damaging the hair and that is durable through several subsequent shampooings.